ANSWER: The Bible says nothing directly about Facebook. The Scriptures were finalized more than 1,900 years before this social media site came to life on the Internet. What we can do, however, is examine how principles found in the Scriptures can be applied to social media Web sites.
Computers allow people to create gossip faster than ever before. Once created, sites like Facebook make it easy for gossip (and for those using it for noblier purposes) to reach a WIDE audience. The audience can be not just your friends or even those who live near you, but the whole world! People can say almost anything online and get away with it, especially when they do so anonymously. Romans 1 lists "backbiters" as a category of sinner to avoid becoming (Romans 1:29 - 30).
Gossip can be true information that attacks other people. It need not be false or half-true. We have to be wary of telling lies, rumors or out-of-context half-truths about others when posting online. God is clear about what it thinks of gossip and lying. He warns us not to be a talebearer to others, which is obviously a temptation on Facebook and other social media platforms (Leviticus 19:16, Psalm 50:20, Proverbs 11:13 and 20:19)
Another problem with social media like Facebook is that it can become addictive and encourage spending too much time on the site itself. Such sites can be a big time waster when one's life should be spent on other activities, such as prayer, studying the word of God, and so on. After all, if someone says, "I don't have time to pray or study the Bible," but finds an hour each day to visit Twitter, etc., that person's priorities are skewed. Using social sites can at times be beneficial or even good, but spending alot of time on them can be wrong.
There is a third problem, though subtle, that social sites can feed. They can encourage interacting with others mainly or solely through electronic means rather than with face-to-face contact. Our relationships can become superficial if we primarily interact with people online and not in person.
There is one text that might relate directly to the Internet and maybe even to Twitter, Facebook and others, "But you, Daniel, shut up the words, and seal the book until the time of the end; many shall run to and fro, and knowledge shall increase" (Daniel 12:4). This scripture may have a dual meaning. It could refer to knowledge of God's holy word increasing and becoming clearer over the years. It could also, however, refer to human knowledge in general increasing at a fast pace, a pace made possible by the computer revolution. Furthermore, since we now have relatively cheap transportation like cars and planes, people are literally running to and fro around the world.
Many technological innovations become good or bad depending on how they are used, not because they exist of themselves. Even a gun can do good, such as when it's used for hunting, but it is evil when used to murder someone. Although Scripture does not specifically address how to use Facebook (or many of the things we use or run into today), its principles can still be applied to guide us on how we should view and use such modern inventions.